Exercise blocks made from firm-but-resilient materials such as foam rubber and equivalents are known, and come in a variety of shapes (wedges, blocks, curved saddles, etc.—hereafter “blocks” for convenience). These prior exercise blocks are often limited to helping the user perform a single exercise, or a small set of closely related exercises, and are accordingly limited in usefulness. Prior exercise blocks also seem to be generally meant for standalone use, i.e. not designed to interact with other exercise devices and supports commonly found in exercise studios and gyms.